‘Do we need to do a better job of making devices that fit female anatomy?’

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Mahmoud B. Malas rises to ask a question during VAM 2021

It was a burning question posed from the conference floor, and it led to some approving social media nods in its aftermath: Does the tone of conversation around the vascular anatomy of females need to morph into a discussion about the availability of devices that fit the female anatomy?

The point was provoked by another question that followed findings delivered by Scott R. Levin, MD, a general surgery resident at the Boston University School of Medicine, Boston, at the 2021 Vascular Annual Meeting (VAM) in San Diego (Aug. 18–21) suggesting female sex was associated with a higher risk of reintervention after endovascular procedures and infrainguinal bypass surgeries for intermittent claudication.

“Do we need to stop saying that women have worse anatomy than men?” came the question from Mahmoud B. Malas, MD, chief of vascular and endovascular surgery at the University of California San Diego, San Diego, in Plenary Session 6 on Aug. 21.

Malas was speaking after fellow audience member Keith D. Calligaro, MD, chief of vascular surgery and endovascular therapy at Pennsylvania Hospital in Philadelphia, rose to query Levin on two aspects of his findings. Calligaro began by referencing a question he had posed the previous day of Thomas F. X. O’Donnell, MD, senior vascular surgery fellow at Beth Israel Deaconess Medical Center in Boston, who had delivered new findings on racial disparities in the treatment of ruptured abdominal aortic aneurysms (AAAs).

Scott R. Levin

“Yesterday I rose to make a comment about a paper that was presented and why women might have higher complication rates for aortic aneurysms,” he explained. “That comment was simply because some of them have smaller iliac arteries, worse access, more complications.”

Could the reason for the higher level of complications among women demonstrated in the claudication study be put down to the fact women “tend to have smaller infrainguinal arteries and therefore less durable long-term results?” Calligaro said, further querying: “You commented women are less likely to be given statins. I’m aware of several papers that have shown women are less likely to take statins when they’re prescribed. I don’t know why. I’ve read several papers on this subject, and I don’t know that anyone really knows the reason, but that’s what a lot of the data shows.”

The data gathered by Levin and colleagues demonstrated that female sex was associated with lower use of aspirin and statins prior to both infrainguinal bypasses and endovascular interventions.

“But we don’t know based on using the database why this is the case,” said Levin. “We do know that aspirin-statin use is associated with lower rates of reintervention, and so the lower rates of aspirin-statin may have contributed to higher reintervention. We did actually control for preoperative medication in our multivariable analysis. Further prospective studies would be needed to tease out the causes of why there are these differences by sex.”

Keith D. Calligaro

For Malas’ part, he asked Levin whether the profession needed “to do a better job of making devices that fit women,” saying it was not that women have “worse anatomy than men” but rather smaller vessels. “Is the problem, with an aneurysm or peripheral intervention, that we don’t make stuff that fits women’s anatomy better?” Levin said that the present study—which queried the Vascular Quality Initiative (VQI) for all suprainguinal and infrainguinal bypasses as well as endovascular interventions for intermittent claudication from 2010–2020—was not able to demonstrate causes, nor did it probe specific devices. “But I think that would be useful for future studies to look at and control for specific devices,” he said.

After performing bivariable and multivariable analyses to evaluate the association of sex with perioperative and long-term outcomes, what the chief findings of the investigation did show was that among endovascular procedures for intermittent claudication, female patients more often had iliac interventions, less often had infrainguinal interventions, and less often underwent stenting or atherectomy (all p<0.05), according to Levin et al.

This was based on 64,752 endovascular interventions (62% male, 38% female sex) prized out of the VQI on claudicants. Furthermore, female patients more often had access site hematomas (3.6% vs. 2.3%; p<0.001) and stenosis or occlusion (0.3% vs. 0.2%; p=0.001). Female patients had lower one- year reintervention-free survival (84.3% vs. 86.3%; p<0.001), with no differences in amputation or death. Female sex was independently associated with one-year reintervention (hazard ratio [HR] 1.16, 95% confidence interval [CI] 1.09–1.24; p<0.001), but not amputation or death.

Among those who underwent infrainguinal bypasses (9,314 surgeries; 70% male, 30% female), female patients had fewer infrapopliteal targets and more often received prosthetic conduits (p<0.05 for all), Levin explained. There were no differences in perioperative outcomes. Female patients had lower one-year reintervention-free survival (79% vs. 81.2%; p=0.04) with no differences in amputation or death. Female sex was independently associated with one-year reintervention (HR 1.16, 95% CI 1.03–1.31; p=0.016), but not amputation or death.

As for suprainguinal bypasses (3,227 surgeries; 63% male, 37% female), “female patients more often underwent bypass from the axillary artery (p<0.05). Female patients had fewer perioperative surgical site infections (0.9% vs. 1.8%; p=0.048). There was no significant difference by sex for one-year reintervention, amputation, or death, even adjusted for comorbidities,” Levin added.

Levin also reported that female patients were less likely to present with independent ambulatory status preoperatively, which persisted postoperatively after endovascular interventions. Meanwhile, for endovascular interventions and infrainguinal bypasses, female patients were less often on aspirin (73.4% vs. 77.3% and 71.5% vs. 74.8%, respectively) and statins (71.8% vs. 76.7% and 73.1% vs. 76%, respectively)—all with a p value of <0.001.

Levin concluded: “Female patients undergoing interventions for claudication were less often on aspirin and statins. Interventionists treating female claudication patients should increase their efforts to maximize medical therapy, even patients exhibiting with worse baseline ambulatory function and worse function after peripheral vascular interventions. After peripheral vascular interventions and infrainguinal bypasses, female patients had increased risk of reintervention. Future research should clarify reasons for poorer intervention durability in female patients.”

Ruptured AAA disparities

The data demonstrating racial disparities among patients treated for rAAAs, delivered by O’Donnell during a special scientific session on diversity, equity and inclusion Aug. 20, included one statistic showing that Black patients were significantly less likely to undergo transfer prior to repair compared to white patients (49% vs. 62%; p=0.002)—with rates of transfer high. “This was consistent in crude and adjusted analyses, in sub-analyses limited to only stable patients, and was not modified by insurance status, type of operation, or hospital volume,” O’Donnell revealed.

Thomas F. X. O’Donnell

O’Donnell and colleagues examined all repairs of rAAA in both the VQI from 2003–2020 to evaluate transfer rates and outcomes in Black vs. white patients in the National Inpatient Sample (NIS) from 2004–2015 to examine turndown rates. They found nearly 5,000 (6.2% Black) in the former and 50,000 (6% Black) in the latter. Mixed effects logistic regression, Cox regression and marginal effects modeling were used to study the interaction between race, insurance status, type of operation—open repair vs. endovascular aneurysm repair (EVAR)—and hospital volume.

There was no significant difference in perioperative mortality (Blacks 22% vs. whites 26%; p=0.098) or complications (52% vs. 52%; p=0.64), the researchers found. But O’Donnell said the data show that Black patients were significantly more likely to be turned down for repair when presenting with rAAA (37% vs. 28%; odds ratio [OR] 1.5 [1.2–1.9]; p<0.001).

“There was a significant interaction between race and insurance status with respect to turndown,” he explained. “Patients with private insurance underwent operations at similar rates regardless of race, but among patients with Medicare or Medicaid/self-pay, Black patients were less likely than whites to undergo repair (Medicare: 64% vs. 72%; p=0.001; Medicaid/self-pay: 43% vs. 61%, p=0.031).”

Furthermore, patients with Medicaid/self-pay were less likely to undergo repair compared to patients of the same race with either Medicare or private insurance (p<0.05), O’Donnell added.

He concluded: “Black patients with rAAA are poorly served by the current systems of interhospital transfer in the United States, as they less often undergo transfer prior to repair. Although postoperative outcomes appear similar, this may be false optimism, as Black patients, especially the underinsured, are more often turned down for repair even after adjustment. Significant work is needed to better understand the reasons underlying these disparities and identify targets to improve the care of Black patients with rAAA.”

Session moderator Bernadette Aulivola, MD, professor of surgery and director of the division of vascular surgery and endovascular therapy at Loyola University Medical Center in Maywood, Illinois, asked O’Donnell to explain how he and his fellow researchers defined turndown, or failure to offer an operation, elaborating, “How do you catch out whether that’s patients too unstable to undergo repair, patients refusing repair, comorbidities such that repair would be futile?”

O’Donnell said: “That’s always the interesting question with something like NIS, and why we wanted to use the two databases, and that’s something you can tease out in the VQI, and we know from the VQI that the rate of presentation in terms of instability is the same, so, all things being equal, the race comorbidities were slightly higher but presentation as an unstable patient was about the same, so some of that increase in turndown may be due to the comorbid burden. But since the instability is about the same, you can’t attribute all of that.”

Calligaro, raising the same point he later asked of Levin the following day, urged caution in how the data is interpreted. “There are several publications also showing that women are less likely to undergo repair at the same size, and that they have a higher mortality for elective and ruptured, open versus endo,” he said. “Frankly, I don’t think it’s because women are turned down for surgery per se. One reason that comes to mind is for instance with EVARs—they may have smaller iliac arteries, worse access and higher complication rates … I’m not aware of any anatomic differences between African Americans in terms of aortoiliac anatomy but there may be other things we’re not aware of.”

O’Donnell accepted the point, explaining that his group had looked at aortoiliac anatomy previously. “What we found in the VQI at least was that Black patients—and similarly in this population as well—had more iliac aneurysms, but more often were actually treated with EVAR. That’s borne out in this dataset: Black patients were about 10% more likely to undergo EVAR. So some of it may be anatomic differences, but I don’t think that can explain a significant portion either.”

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